in georeferencer, filename confusion with multiple georeferencing

[fhof]

Context:
While georeferencing multiple maps with a simple linear transformation.

How to reproduce:

• Using the plug-in, georeference a first image (for ex. map1.png).
  
• When completed, open an unrelated image (for ex. map2.png), and answer "No" when asking if existing points have to be saved.
  
• Define enough points for the georeferencing.
  
• Click on "Start georeferencing". A dialog warns that the image already contains georeferencing data, which is not the case. It is a confusion with the previously georeferenced image. The warning proposes either to overwrite the world file or to cancel.

Workaround:

• Go into "Transformation settings". It show you the same parameters as for the previous georeferencing.
  
• Just click OK, the parameters will be reapplied, with the current image path being considered.
  

Although the workaround is simple, the behavior is a bit strange. When not paying enough attention on the warning message, some existing data would be overwritten.

[mhugent]

Fixed in r13739